NIAID CEIRS | Research Publication Commentary
In a recent report published in Science, CEIRS investigators were part of a group of researchers in the Netherlands that investigated similarities and differences in pathogenesis of COVID-19, MERS, and SARS in cynomolgus macaques (Rockx 2020). Prior to this study, little information on the pathogenesis of SARS-CoV-2 infection was available. Investigators were aiming to characterize the pathogenesis of SARS-CoV-2 infection and compare findings to the pathogenesis of MERS-CoV and SARS-CoV.
In this study, investigators experimentally infected cynomolgus macaques with SARS-CoV-2. Two age groups were studied, young adults and old adults, to determine if there are differences in pathology due to age. Virus shedding in nasal, throat, and rectal swabs was assayed using RT-qPCR and virus culture. Autopsies were performed to characterize histopathological changes in the lungs and to determine which tissues were infected by the virus. To provide comparisons for the pathology and virology findings, a separate group of cynomolgus macaque were infected with MERS-CoV; historical data on SARS-CoV infection was also used for comparison.
Rockx et al. found that all animals were successfully infected with SARS-CoV-2, although they showed no clinical signs of infection. Virus shedding in nasal swabs and throat swabs peaked earlier in young adult group compared to the older adult group. SARS-CoV-2 RNA was not detected in rectal swabs, with the exception of one rectal swab from one animal during the study. Investigators did not observe virus replication in any organ system other than the respiratory tract but did detect virus RNA in lymph nodes of some animals. The infectious titers of MERS-CoV and SARS-CoV-2 in the respiratory tract were similar to each other but lower than SARS-CoV. SARS-CoV-2 shedding also peaked earlier than SARS-CoV shedding.
This study showed that cynomolgus macaques are a good model of infection for SARS-CoV-2. Further studies should be performed to characterize the differences in pathogenesis between SARS-CoV, MERS-CoV, and SARS-CoV-2. In addition, the cynomolgus macaque model can be used to evaluate potential SARS-CoV-2 treatments and vaccines.